rgb levels, a display-referred module, was used before filmic to brighten the image
after filmic, level was used to stretch the histogram
All of that was done in Rec709, and then exported as Adobe RGB.
Normally, exposure is used to set mid-grey correctly. It seems the 2nd patch above ‘black’ was close to mid-grey, as using that as the sampling point in exposure (and disabling rgb levels) resulted in a correction which then caused the filmic auto-white picker to read 2.81 EV (18% mid-grey is about -2.5 EV).
BTW, all the grey patches resulted in different white balance readings (set white balance to camera reference, enabled color balance, picked the WB from each grey. Correlated colour temperature readings:
background: 4694 K
lightest patch: 4486 K (‘white’?)
then 4504 K
4664 K
5047 K (‘mid grey’ ?)
5469 K
4619 K (‘black’ ? It’s not as dark as the ‘CM’ card)
White on the ‘CM’ card: 4856 K
I don’t know what caused the discrepancy between the darkroom and the export - could it be that the 100% white of the working space, Rec709, is simply brighter than the 100% white of AdobeRGB, so during export it was mapped to a less bright value?
So, I’ve created a 100% image in Gimp, and assigned the profile elles_icc_profiles/ClayRGB-elle-V2-g22.icc at master · ellelstone/elles_icc_profiles · GitHub to it.
Loaded it into darktable and exported it to JPG without modifications using both ClayRGB-elle-V2-g22 and Adobe RGB (compatible). Loaded them both back to darktable; they are all pure white. So, my guess regarding ‘the 100% white of the working space, Rec709’ being ‘brighter than the 100% white of AdobeRGB’, is clearly wrong. Shows how little I know about colour management.
You can set the histogram profile to sRGB or to Adobe…set a color picker in the image…Toggling back and forth and noting the values and then knowing this shows you how the image would change when the Adobe values were assumed to be sRGB in a non color managed app…if color managed it should not be an issue…at least in my experience
I’ve solved the exporting problem!!! I re-installed darktable applied advice from @priort and @priort, and it worked. Thank you all for the effort!
One last thing, I wonder are there any modules in darktable similar to the white slider in photoshop?
I’d like to correct the current RGB values to corresponding ideal values on the colorchecker.
